Submitted to: Vaccine
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/6/2008
Publication Date: 5/6/2008
Citation: Toro, H., Tang, D.C., Suarez, D.L., Shi, Z. 2008. Protection of chickens against avian influenza with non-replicating adenovirus-vectored vaccine. Vaccine. 26:2640-2646.
Interpretive Summary: Avian influenza virus can cause serious disease outbreaks in poultry, including chickens and turkeys. Vaccines can be used to control outbreaks of disease and are used widely in some parts of the world. Current vaccines, however, require that individual birds be picked up and injected, which is a time and labor intensive. A new type of vaccine for avian influenza uses a human adenovirus as a carrier of the avian influenza protein. The adenovirus vector is modified so that it still infects, but it can’t reproduce making it very safe. This study showed that the adenovirus vaccine can be used to vaccinate chicken embryos inside the egg, which is commonly done in the poultry industry. This "in ovo" approach greatly facilitates vaccination of large numbers of animals. The vaccine was shown to protect against a virulent challenge of H7 avian influenza. Additional studies are needed to estimate how this vaccine may perform in field evaluations.
Technical Abstract: Protective immunity against avian influenza (AI) virus was elicited in chickens by single-dose vaccination with a replication competent adenovirus (RCA) -free human adenovirus (Ad) vector encoding a H7 hemagglutinin gene from a low pathogenic North American isolate (AdChNY94.H7). Chickens vaccinated in ovo with an Ad vector encoding an AI H5 (AdTW68.H5) previously described, which were subsequently vaccinated with AdChNY94.H7 post-hatch, responded with robust antibody titers against the H5 and H7 AI proteins. Antibody responses to Ad vector vaccination follow a dose-response kinetic. Moreover, use of a synthetic AI H5 gene codon optimized to match the chicken cell tRNA pool was more potent than the cognate H5 gene.